1. Field of the Invention
The present invention generally concerns torsional damper devices.
2. Description of the Prior Art
There is described in the copending U.S. patent application Ser. No. 686,475 filed on Dec. 26, 1984 and assigned to the assignee of the instant application a torsional damper device for an automotive vehicle clutch, wherein at least two coaxial parts are mounted to rotate relative to each other against circumferentially acting elastic means disposed therebetween within limits of relative angular movement determined by meshing means with clearance provided between the coaxial parts in cooperation with centering means adapted to urge the coaxial parts in the circumferential direction towards an intermediate rest position between the limits of relative angular movement. The centering means comprises at least one elastic member constituting part of the circumferentially acting elastic means colocated with the meshing means with clearance of the coaxial parts and adapted, for the rest position of the latter, to bear at each of its circuferential ends against shoulders of the coaxial parts which are oblique to each other. The shoulders are thus oblique to each other as the flanks of a dovetail groove. The elastic member comprises a simple circumferentially elongate block of elastic material which is disposed chordally of the damper device. The circumferential ends of the elastic member are free of any covering and adapted to bear directly against the corresponding shoulders of the coaxial parts between which it is circumferentially disposed.
Surprisingly, and going completely against the usual provisions in this regard, it has been found that it is possible to make effective use for the necessary elastic member of a simple block of elastic material, without there being any systematic major risk of shearing or tearing of the block, although it then has to cooperate directly with shoulders each formed in practice by the edge of a metal flange, necessarily of reduced axial thickness.
This result is all the more surprising in that, on the one hand, for one of the coaxial parts at least both shoulders with which each of the two circumferential ends of an elastic material block must respectively cooperate are oblique relative to each other, in the manner of the flanks of a dovetail groove, and this results in the presence in this coaxial part of relatively sharp spurs each oriented in the direction towards the median area of the aforementioned circumferential ends, and in that, on the other hand, a block of this kind is called upon when in service to function essentially in shear and is therefore more especially stressed by the shoulders against which it is then engaged.
A general object of the present invention is to provide for various improvements to an elastic material block of this kind so as to further increase its service life and/or to improve its in-service operating conditions.